* Reorganised the doc wiki's todo/* pages, using a link/tag to flag

* Reorganised the doc wiki's todo/* pages, using a link/tag to flag
* Allow pagetemplate plugins to override *anything* in the template.
* Add a meta plugin, which allows specifying various metadata about pages,
  like license and author. It also allows for inserting html link and meta
  tags into html, overriding the title, and adding hidden WikiLinks, which
  can be useful when using link-based globbing for page categorisation.
* Remove preprocessor directives from inlined pages.
* Allow simple preprocessor directive values to be specified w/o quotes.